The impact of dialysis therapy on metabolic syndrome traits at the Groote Schuur Hospital

Abstract

Background The metabolic syndrome (MS) is a clustering of cardiovascular (CV) risk factors and is noted to be increasing globally. Several studies have shown a link between the MS, chronic kidney disease (CKD) and end-stage renal disease (ESRD) possibly through a process of inflammation. Dialysis therapy may increase inflammation and could worsen MS and increase CV risk and diseases in ESRD patients. ESRD has been associated with increased CV disease in dialysis patients. Although there have been several reports on the prevalence of MS from the general population as well as from other specific groups, there are no known studies in South Africa on the prevalence of MS in ESRD patients on chronic dialysis therapy. The prevalence and risk factors for CV diseases are also currently unknown in the dialysis population in Cape Town. Aim The aim of this study was to determine the prevalence of MS in the dialysis population at Groote Schuur Hospital in Cape Town, to determine the effect of dialysis on MS and its traits and to evaluate CV risk in this patient group. Methods A total of 143 prevalent chronic dialysis patients who consented were used for this study. Demographic and relevant clinical details including systolic and diastolic blood pressures, waist and hip circumference and body mass index were obtained from all patients. Blood was drawn in the fasting state for assessment of full lipogram, glucose, ferritin, iron, calcium and phosphate. The metabolic syndrome was defined using the Adult Treatment Panel III (ATPIII) criteria. To determine the impact of dialysis on MS and its traits in our patients, only incident (new) patients starting dialysis were followed up for assessment of MS traits at timed intervals (at baseline, at 6 months and at 12 months) following initiation of chronic dialysis. To evaluate CV risk in this study, common traditional CV risk factors were assessed and were stratified according to number of risk factors as low ( ≤ 1), moderate (2 – 4) or high ( ≥ 4). Relevant statistical methods were used for analysis. Results Of the 143 patients in the study, 67.8% were on haemodialysis (HD) and 32.2% were on peritoneal dialysis (PD). The mean age of all the patients was 38.5 ± 10.4 years. The MS was present in 37.1% of all patients (PD – 52.2%, HD 29.9%; p = 0.015) and the frequency of increased waist circumference and hypertriglyceridaemia were significantly higher in PD patients than HD patients (p < 0.0001 and p = 0.006 respectively). Hypertension was the most prevalent MS trait in all the patients (89.5%) and was also the most prevalent trait in males (92.4%), females (85.9%) and in HD and PD patients (91.3% and 88.7% respectively). The frequency of CV risk was 3.5, 75.5 and 21.0% respectively for low, moderate and high CV risk and there was no difference in CV risk in HD and PD patients. High CV risk correlated with body mass index (BMI), increased waist circumference (WC), hyperphosphataemia, raised calcium – phosphate product, raised parathyroid hormone (PTH) and elevated C-reactive protein (p < 0.05). There was no significant change in MS prevalence or prevalence of MS traits in patients who were followed up irrespective of gender or modality of dialysis (p > 0.05) Conclusion The prevalence of the MS is higher in dialysis patients compared to the general population in South Africa and among dialysis patients, the prevalence is higher in PD than HD patients. Patients with MS have significantly higher CV risk factors than those without MS. Although dialysis therapy appear to have no significant effects on the prevalence of the MS or its traits in this study, the increased prevalence of the MS and CV risk factors may be related to the underlying disease process associated with ESRD. There is therefore an urgent need to identify and treat dialysis patients with the MS in order to reduce CV morbidity and mortality in this group of patients. Further prolonged prospective studies are needed to clarify the impact of dialysis on the MS and its traits in the ESRD population.